Caselaw Visualizations

Trends in Epidemic Lawsuits – A Culture of Litigation?

According to several media outlets, the COVID-19 global pandemic shares many similarities to the Spanish Flu.

Just like COVID-19, the Spanish Flu “started as a mild flu season, not different from any other. When its first wave hit in the spring of 1918, the Spanish flu seemed like just another flu. But then the second wave began at the end of summer.

Spanish flu was the most devastating pandemic ever recorded, leaving major figures like medical philanthropist Bill Gates to draw comparisons to the ongoing COVID-19 pandemic.”

Peter Schelden, What 1918 Spanish Flu Death Toll Tells Us About COVID-19 Coronavirus Pandemic, MedicineNet; see also Forbes, World Economic Forum, The Economist, & Vox


Instructions: Explore the interactive data visualizations on this site by clicking on the data points you wish to learn more about. You may zoom into timelines by selecting the horizontal span you wish you see.

Troubleshooting: If you experience issues viewing or interacting with the visualizations, please use a non-Firefox desktop browser.


While the medical and economic similarities are still being studied, one crucial different is already apparent:

The Spanish Flu, also known as the Influenza Pandemic of 1918-1919, did not leave a heavy footprint in American caselaw. In fact, 2 of the 4 total cases referring to the Spanish Flu only do so once and only as a way to analyze the actual topic of the cases, which were the Swine Flu (1978) and COVID-19 (2020).

In the previous post, “Epidemiology through Caselaw – Learning From Yellow Fever,” we noted how the geographical spread and historical epidemics of diseases can be analyzed and visualized through empirical analyses of caselaw. But why is it that there are already 1000+ “COVID-19” cases filed, when the supposedly comparable Spanish Flu barely left a mark in caselaw? Of course, the total number of published substantive cases in the dataset has significantly increased since 1918, but not sufficiently to account for the sheer number of immediately filed COVID-19 cases:

To get a better sense of how the legal footprints of recent epidemics differ from earlier crises, let’s take a look at three early 20th-century epidemics in comparison to the HIV, Hepatitis B, and Swine Flu outbreaks in the late 20th and early 21st centuries.


While it is clear that the number of HIV-related cases far surpassed that of the earlier epidemics, the story for Hepatitis B and Swine Flu is not as clear. The epidemiological statistics shown below also do not provide a clear explanation.

HIV ~1 million

At the end of 2017, there were 1,018,346 adults and adolescents with diagnosed HIV in the US and dependent areas.

HIV Statistics Overview, CDC

Hepatitis B ~ 1 million

An estimated 862,000 people are living with Hepatitis B virus in the United States.

Viral Hepatitis, CDC, Updated 9, 2019

Swine Flu

From April 12, 2009 to April 10, 2010, CDC estimated there were 60.8 million cases (range: 43.3-89.3 million), 274,304 hospitalizations (range: 195,086-402,719), and 12,469 deaths (range: 8868-18,306) in the United States due to the (H1N1)pdm09 virus.

2009 H1N1 Pandemic, CDC

From this primary glance at the data, it seems that each disease and outbreak has an idiosyncratic impact on American caselaw. The health-related, business-related, insurance-related COVID-19 cases will reflect the unique circumstances we find ourselves in during this unprecedented global pandemic.

Related Visualizations


Word frequency for each state is determined by dividing the number of times the target phrase appears over the total number of words each state’s corpus (the total combined body of caselaw).

Word Frequency =(Word Count of the Target Phrase)/(Total Word Count)

Case frequency for each state is determined by dividing the number of cases that contain the target phrase over the total number of cases in each state.

Case Frequency =(Cases that Contain the Target Phrase)/(Total Number of Cases)


Do you have any guesses or explanations about the findings shown above? Do you have any additional visualizations concerning epidemiology and law? Let me know @JoaoMarinotti on Twitter. This post is part of the Caselaw Visualizer Project. For a description of the dataset and the processes used to generate these visualizations, click here. The data was made available by the Harvard Law School Library’s Case Access Project (found at Case.Law). For information about me, click here.